JP2023158109A - Absorbent article - Google Patents

Abstract

To provide an absorbent article (1) realizing excellent wearing comfort.SOLUTION: An absorbent core (10) has crushed fibers. The crushed fibers include water-retaining fibers (50L) made from hardwood. The absorbent core (10) is provided with a compressed part (40), in which the density of the absorbent core (10) is higher than the density of the surroundings thereof. The compressed part (40) has a first dimension and a second dimension, which is orthogonal to the first dimension and has a length longer than the first dimension. The maximum value of the first dimension of the compressed part (40) is greater than the average fiber length of the water-retaining fibers (50L) made from hardwood.SELECTED DRAWING: Figure 1

Description

The present invention relates to absorbent articles.

A sanitary napkin that absorbs excretory fluids such as menstrual blood is known as an example of an absorbent article. Such sanitary napkins include an absorbent core (absorbent core), and the absorbent core contains water-retentive fibers. Usually, softwood pulp fibers having a long fiber length are used as water-retaining fibers. Moreover, Patent Document 1 also discloses that a hardwood pulp fiber having a fiber length shorter than that of a softwood pulp fiber is used as a water-retentive fiber.

Special Publication No. 2004-538024

Generally, absorbent articles are provided with a compression section on the absorbent body in order to improve absorption performance, fit to the body, and the like. If, for example, softwood pulp fibers are used as water-retentive fibers in the absorbent core of sanitary napkins, which are generally called thin, the compressed part of the absorbent material becomes too hard, causing discomfort to the wearer. There was a risk.

Further, in the absorbent article of Patent Document 1, hardwood pulp fibers that are softer than softwood pulp fibers are used, but they are formed using the same manufacturing method as nonwoven fabrics (air-laid method), and a binding material is added. Furthermore, the binding material increases the rigidity too much, which may cause discomfort to the wearer.

The present invention was made in view of the above-mentioned problems, and its purpose is to provide an absorbent article that reduces the hardness felt by the body and provides a comfortable wearing feeling. be.

The main invention for achieving the above object has a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other, and includes a liquid-permeable top sheet, a liquid-impermeable back sheet, and the top sheet and the liquid-impermeable back sheet. An absorbent article comprising: an absorbent core provided between a backsheet and a backsheet, the absorbent core having pulverized fibers, and the pulverized fibers including hardwood fibers. The absorbent core is provided with a compressed portion in which the density of the absorbent core is higher than the density of its surroundings, and the compressed portion has a first dimension and a a second dimension that is perpendicular to the first dimension and has a length equal to or longer than the first dimension, and the maximum value of the first dimension of the compressed portion is the average of the water-retentive fibers made of the hardwood. This is an absorbent article characterized by being longer than the fiber length.

Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

According to the present invention, it is possible to provide an absorbent article that has reduced hardness felt by the body and is comfortable to wear.

FIG. 2 is a schematic plan view of the napkin 1 viewed from the skin side in the thickness direction. 2 is a schematic cross-sectional view taken along the line AA in FIG. 1. FIG. FIG. 2 is a diagram showing the fiber length distribution of hardwood pulp fibers and softwood pulp fibers. FIG. 3 is a diagram for explaining a method of manufacturing the absorbent body 10. FIG. FIG. 2 is an explanatory diagram showing how the fibers of the second sheet 4 and the fibers of the absorbent body 10 are intertwined. FIG. 2 is a schematic cross-sectional view of the pressing section 40 taken along the line BB in FIG. 1. FIG. FIG. 4 is a diagram for explaining the horizontal and vertical dimensions of the pressing section 40. FIG. It is a schematic sectional view showing the pressing part of hardwood pulp 50L and softwood pulp 50N. It is an explanatory view for explaining deformation of the compression part of hardwood pulp 50L. FIG. 2 is a schematic plan view of the napkin 1 viewed from the non-skin side in the thickness direction. FIG. 4 is an explanatory diagram for explaining a method for evaluating the tensile strength of the compressed portion 40. FIG. These are the evaluation results of the density (Table 1) and tensile strength (Table 2) of the compressed portion 40. FIG. 3 is a diagram (Table 3) showing the evaluation results of absorbent density and average fiber length of water-retaining fibers. FIG. 4 is a diagram (Table 4) showing the average interfiber distance Dp of fibers. FIG. 2 is a diagram showing the fiber width distribution of hardwood pulp and softwood pulp. 1 is a schematic cross-sectional view of a napkin 100 having a core wrap sheet 11. FIG.

From the description of this specification and the attached drawings, at least the following matters will become clear.

A liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent material having a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other, and provided between the top sheet and the back sheet. an absorbent article comprising a core, the absorbent core having pulverized fibers, the pulverized fibers containing water-retentive fibers made of hardwood, and the absorbent core comprising: The absorbent core is provided with a compressed part in which the density of the absorbent core is higher than the density of its surroundings, and the compressed part has a first dimension, which is perpendicular to the first dimension and is equal to or larger than the first dimension. and a second dimension having a length of, and the maximum value of the first dimension of the compressed portion is larger than the average fiber length of the water-retentive fiber made of the hardwood. Absorbent articles.

According to such an absorbent article, it is possible to provide an absorbent article in which the hardness felt by the body when the compressed portion is deformed is reduced and a comfortable wearing feeling is realized.

In such an absorbent article, it is preferable that the compressed part has a hinge part in which the absorbent core and a sheet on the skin side of the absorbent core are integrally compressed.

According to such an absorbent article, the absorbent core containing water-retentive hardwood fibers tends to twist easily, so by providing the hinge portion, twisting of the absorbent core can be suppressed.

In such an absorbent article, it is desirable that the hinge portion is formed by pressing the top sheet and the absorbent core together.

According to such an absorbent article, by bringing the distance between the top sheet and the absorbent core closer, it is possible to improve the liquid transferability to the absorbent body and to suppress twisting.

In such an absorbent article, the absorbent article has a wing portion for fixing the absorbent article to the crotch of a wearer's underwear, and the hinge portion has a wing portion that has the width A central hinge portion having the second dimension in the longitudinal direction is provided in a region between a front extension start point and a rear extension start point in the longitudinal direction that extend outward in the longitudinal direction. Preferably, the maximum value of the first dimension of the central hinge portion is greater than the average fiber length of the water-retaining fibers made of hardwood.

According to such an absorbent article, it is possible to provide an absorbent article in which the hardness felt by the body when the compressed portion is deformed in the central hinge portion is reduced, and a comfortable wearing feeling is realized.

In such an absorbent article, the hinge portion includes a base compressed portion and a high-density compressed portion compressed in the base compressed portion to a higher density than the base compressed portion, and the high-density compressed portion is compressed at a higher density than the base compressed portion. It is desirable that the maximum value of the dimension of the portion in the longitudinal direction is larger than the average fiber length of the water-retaining fibers made of the hardwood.

According to such an absorbent article, the hinge portion can be easily deformed in the longitudinal direction in the high-density compressed portion.

In such an absorbent article, it is desirable that the hinge portion has a wavy shape when viewed from the thickness direction.

According to such an absorbent article, since the wave shape makes it difficult for force to concentrate at one point compared to the straight shape, it is possible to suppress the absorbent article from losing its shape.

In this absorbent article, the compressed part includes a peripheral compressed part compressed along the outer peripheral edge of the absorbent article, and the maximum value of the first dimension of the peripheral compressed part is the same as that of the hardwood. It is desirable that the average fiber length is longer than the average fiber length of the water-retaining fibers.

According to such an absorbent article, even if the absorber is included in the peripheral edge, the rigidity can be reduced, so deformation (folding tendency) of the peripheral edge can be suppressed.

In this absorbent article, the absorbent article includes a second sheet made of fibers, the second sheet is provided adjacent to the skin side of the absorbent core, and the second sheet is provided adjacent to the skin side of the absorbent core, and the second sheet is made of fibers. At least a portion of the pulverized fibers protrude from the skin-side surface of the absorbent core and extend into the second sheet, and at least a portion of the crushed fibers protrude from the skin-side surface of the absorbent core and extend into the second sheet. Desirably, it is in contact with the fibers of the sheet.

According to such an absorbent article, menstrual blood and the like can easily enter the inside of the absorbent core through mutual fibers, and the liquid absorption rate can be increased.

In such an absorbent article, it is desirable that the absorbent core has a density of 0.04 g/cm ³ or more and less than 0.3 g/cm ³ .

According to such an absorbent article, it is possible to provide an absorbent article that is comfortable to wear with less discomfort.

In such an absorbent article, the compressed portion has a density of 0.2 g/cm ³ or more and less than 0.8 g/cm ³ , and when the joint portion between the absorbent core and the compressed portion breaks due to tension. It is desirable that the tensile strength, which is the maximum tensile force, is 0.5 N/25 mm or more and less than 1.0 N/25 mm.

According to such an absorbent article, it is possible to provide an absorbent article that is comfortable to wear with less discomfort.

In such an absorbent article, it is desirable that the absorbent article has a torque value of 4 mN·m or more and less than 10 N·m.

According to such an absorbent article, it is possible to provide an absorbent article that is comfortable to wear with less discomfort.

In this absorbent article, the absorbent article includes a second sheet made of fibers, and in the absorbent core, a plurality of the pulverized fibers are intertwined with each other, and the top sheet and the second sheet are intertwined with each other. It is desirable that the average inter-fiber distance of the sheet is larger than the average inter-fiber distance of the pulverized fibers, and the average inter-fiber distance of the pulverized fibers is 5 μm or more and less than 40 μm.

According to such an absorbent article, excretory fluid quickly reaches the absorbent core, the capillary effect is likely to act, and an absorbent article with good absorbency can be provided.

In such an absorbent article, the absorbent core is provided with a low basis weight part in which the basis weight of the absorbent core is lower than the basis weight of the surrounding area, and the low basis weight part is It is desirable that a depression shape is formed on the surface of the elastic core, and that the maximum value of the first dimension of the low basis weight portion is larger than the average fiber length of the water-retentive fibers made of the hardwood.

According to such an absorbent article, it is possible to provide an absorbent article that reduces discomfort and provides a comfortable wearing feeling.

In this absorbent article, a plurality of slip preventers extending in a first direction are provided on the non-skin side of the backsheet at intervals in a second direction perpendicular to the first direction, and the slip preventers are provided at intervals in a second direction perpendicular to the first direction. It is desirable that the minimum value of the interval in the second direction of the stops is greater than the average fiber length of the water-retaining fibers made of the hardwood.

According to such an absorbent article, since the absorbent core is easily bent between the slippage stops, the absorbent article can easily move in conjunction with body movements, and the fit is improved.

In this absorbent article, the absorbent article has a core wrap sheet that covers the outer peripheral surface of the absorbent core, and the core wrap sheets are provided at intervals in the width direction. The absorbent core is bonded to the absorbent core by the core wrap bonding agent extending in the longitudinal direction, and the minimum value of the interval in the width direction of the core wrap bonding agent is greater than the average fiber length of the water-retentive fibers made of the hardwood. Larger is desirable.

According to such an absorbent article, the portion to which the core wrap bonding agent is not applied is easily deformed, so it is possible to provide an absorbent article that is compatible with preventing the absorbent core from losing its shape and having conformability.

In such an absorbent article, the average fiber width of the water-retentive fibers made of the hardwood is 15 μm or less, and the number of water-retentive fibers made of the hardwood contained per unit area of the absorbent core is 300 pieces/ It is desirable that the number of water-retaining fibers is at least 2 mm2 and less than 2,500 fibers/mm2, and that a superabsorbent polymer is present between a plurality of water-retaining fibers made of the hardwood.

According to such an absorbent article, the excreted liquid contained in the hardwood pulp is easily drawn into the superabsorbent polymer between the hardwood pulps, so that liquid return can be reduced even when excreted liquid is absorbed multiple times. I can do it.

In such an absorbent article, the standard deviation of the fiber length of the water-retaining fiber made of the hardwood is 0.27 or less, and the standard deviation of the fiber width of the water-retaining fiber made of the hardwood is 7.55 or less. is desirable.

According to such an absorbent article, it is easy to maintain a uniform fiber density in the absorbent body, so that the fibers are easily diffused concentrically with less deviation in the plane direction.

In such an absorbent article, the value obtained by adding the standard deviation of the fiber length of the water-retaining fibers made of hardwood to the average fiber length of the water-retaining fibers made of hardwood is the average fiber length of the water-retaining fibers made of hardwood. The value obtained by subtracting the standard deviation of the fiber length of the water-retaining fibers made of hardwood from the average fiber length of the water-retaining fibers made of hardwood is less than twice the length of the water-retaining fibers made of hardwood. It is desirable that the average fiber length is greater than 1/2 of the average fiber length.

According to such an absorbent article, it is easy to maintain a uniform fiber density in the absorbent body, so that the fibers are easily diffused concentrically with less deviation in the plane direction.

In such an absorbent article, the absorbent core includes a plurality of thermoplastic fibers, and has a compression section that integrally compresses the absorbent core in the thickness direction, and in the compression section, , it is desirable that the thermoplastic fibers are fused to each other.

According to such an absorbent article, even when the wearer moves his or her body significantly, it is possible to easily prevent the absorbent core 10 from losing its shape or from deteriorating its water absorbency.

===Embodiment===
<<Basic composition of sanitary napkins>>
A sanitary napkin 1 (hereinafter also simply referred to as napkin 1) will be described as an example of an absorbent article according to the present embodiment. In the following explanation, a sanitary napkin will be explained as an example of an absorbent article, but the absorbent article of this embodiment also includes a so-called vaginal discharge sheet (for example, a panty liner), a light incontinence pad, a urine absorbing pad, etc. and is not limited to sanitary napkins.

FIG. 1 is a schematic plan view of the napkin 1 viewed from the skin side in the thickness direction. FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. Furthermore, in the following description, each direction will be defined as shown in FIGS. 1 and 2. That is, the "longitudinal direction" along the product longitudinal direction of the napkin 1, the "width direction" perpendicular to the longitudinal direction along the product transverse direction of the napkin 1, and the "thickness" perpendicular to the longitudinal direction and the width direction, respectively. Define "direction". In the longitudinal direction, the direction facing the wearer's ventral side when using the napkin 1 is defined as the "front side", and the direction facing the wearer's back side is defined as the "rear side". In the thickness direction, the side that comes into contact with the wearer's skin when the napkin 1 is worn is defined as the "skin side (upper side)", and the opposite side is defined as the "non-skin side (lower side)".

The napkin 1 is a sheet-like member having a vertically elongated shape in a plan view, and includes a pair of side sheets 2, a top sheet 3, a second sheet 4, an absorbent body 10, a cover sheet 6, and a back sheet 5 in the thickness direction. The skin is laminated in order from the skin side to the non-skin side (see Fig. 2). Each of these members is bonded to an adjacent member in the thickness direction using an adhesive such as hot melt adhesive (HMA). Note that examples of the adhesive application pattern include an Ω pattern, a spiral pattern, and a stripe pattern.

The napkin 1 also includes a napkin main body 20 provided with the absorbent body 10, and a pair of wing parts 30 extending from the longitudinal center region of the napkin main body 20 to both outer sides in the width direction. The longitudinal center area where the wing portion 30 is provided (also referred to as wing area WA. More specifically, the front extension start point t1 in the longitudinal direction where the wing portion 30 extends outward in the width direction and the rear extension point t1) The area between the starting point t2 (see FIG. 1) is the area that comes into contact with the wearer's excretion opening (crotch area) when the napkin 1 is used.

The top sheet 3 is a member that comes into contact with the wearer's skin when the napkin 1 is used, and allows liquid such as menstrual blood to permeate from the skin side to the non-skin side in the thickness direction and transfer to the absorbent body 10. Therefore, for the top sheet 3, an appropriate liquid-permeable flexible sheet such as an air-through nonwoven fabric is used.

The second sheet 4 is a sheet made of liquid-permeable fibers, and may be made of the same air-through nonwoven fabric as the top sheet 3. The second sheet 4 is provided on the skin side of the absorbent body 10 (adjacent to the skin side), and plays roles such as preventing the return of excreta such as menstrual blood, improving the diffusion of excreta, and improving cushioning properties. . However, the napkin 1 does not need to have the second sheet 4 (for example, the top sheet 3 may be used instead).

The cover sheet 6 may be a liquid-permeable sheet or a liquid-impermeable sheet, and examples include tissue paper and SMS (spunbond/meltblown/spunbond) nonwoven fabric. The cover sheet 6 is provided between the absorbent body 10 and the back sheet 5. That is, the napkin 1 includes a cover sheet 6, the cover sheet 6 is joined to the absorbent body 10 adjacent to the non-skin side of the absorbent body 10, and the back sheet 5 is connected to the 6 non-skin side of the cover sheet. It is joined to the cover sheet 6 adjacent to the side. However, the napkin 1 does not need to have the cover sheet 6 (for example, the back sheet 5 may be used instead).

The backsheet 5 prevents liquid that has passed through the topsheet 3 and been absorbed by the absorbent body 10 from seeping out to the clothing side (non-skin side) such as underwear when the napkin 1 is used. For the back sheet 5, an appropriate liquid-impermeable flexible sheet such as a polyethylene (PE) resin film is used. Note that the top sheet 3 and the back sheet 5 have a planar size larger than that of the absorbent core 10.

The side sheet 2 may be a liquid-permeable sheet or a liquid-impermeable sheet, and examples include SMS nonwoven fabric and the same air-through nonwoven fabric as the top sheet 3.

As shown in FIGS. 1 and 2, the outer peripheral edges of the side sheet 2, top sheet 3, and back sheet 5 are joined by adhesive or welding, so that there is no absorption between these sheets. A body 10 is held. Further, the pair of side sheets 2 extend outward in the width direction from both sides of the top sheet 3 in the width direction, and form a pair of wing portions 30 together with the back sheet 5.

Appropriate adhesive (for example, hot melt adhesive) is applied to the non-skin side surface of the napkin main body 20 in the thickness direction (that is, the non-skin side surface of the back sheet 5) in a plurality of strip-shaped regions along the longitudinal direction. A main body adhesive part 21 (corresponding to a slip prevention member) is provided (see FIGS. 2 and 10). That is, on the non-skin side of the backsheet 5, a plurality of slip preventers extending in the longitudinal direction are provided at intervals in the width direction. When the napkin 1 is used, the main body adhesive part 21 is attached to the side of the skin of underwear, etc., thereby fixing the napkin 1 to the underwear, etc.

Similarly, a wing adhesive portion 31 is provided on the non-skin side surface of each wing portion 30 in the thickness direction (that is, the non-skin side surface of the backsheet 5) (see FIG. 2). When the napkin 1 is used, the wing portion 30 is bent toward the non-skin side, and the wing adhesive portion 31 is attached to the non-skin side of the underwear, etc., thereby fixing the napkin 1 to the underwear or the like. That is, the wing part 30 is a part for fixing the napkin 1 to the crotch area of the wearer's underwear.

The absorbent body 10 (corresponding to an absorbent core) is a vertically elongated member that is long in the longitudinal direction, and absorbs liquid (excrement) such as menstrual blood and retains it inside. Details of the absorber 10 will be described later. The second sheet 4, the absorbent core 10, and the cover sheet 6 have the same planar shape and are laminated in the thickness direction. Note that in this embodiment, these members are bonded to each other by hot melt adhesive (HMA), but they do not need to be bonded.

Further, the napkin 1 is provided with a plurality of compressed portions 40 (recessed portions) (see FIG. 1). The compressed portion 40 is a portion that is recessed from the skin side toward the non-skin side in the thickness direction, and is a portion where the density of the absorbent core 10 is higher than the density of the surrounding area. Details of the compressing section 40 will be described later.

<<About the absorber 10>>
The absorbent body 10 has water-retaining fibers that absorb liquid, and is formed into a vertically elongated shape when viewed from above. Further, the absorbent body 10 may contain materials other than water-retentive fibers (for example, thermoplastic resin fibers). When the absorbent body 10 includes water-retaining fibers and thermoplastic resin fibers, the absorbent body 10 is formed in a state where these fibers are mixed with each other.

Examples of water-retentive fibers include pulp, such as wood pulp obtained from softwood (e.g., southern yellow pine) or hardwood (e.g., eucalyptus), bagasse, kenaf, bamboo, hemp, cotton (e.g., cotton linter), etc. Examples include non-wood pulp; regenerated cellulose fibers such as rayon fibers; and semi-synthetic fibers such as acetate fibers. Usually, softwood pulp with a long fiber length is often used as the water-retaining fiber.

FIG. 3 is a diagram showing the fiber length distribution of hardwood pulp fibers (hereinafter also referred to as hardwood pulp, equivalent to water-retentive fibers made of hardwood) and softwood pulp fibers (hereinafter also referred to as softwood pulp). The horizontal axis shows fiber length (mm), and the vertical axis shows frequency (%). As shown in the figure, the average fiber length of the softwood pulp is 2.5 mm, and the fiber length distribution width is wide (including fibers of 3 mm or more. Standard deviation is 1.6). On the other hand, the average fiber length of hardwood pulp is 0.79 mm, and the fiber length distribution width is narrow (standard deviation is 0.27). Note that the definition, measurement method, etc. of the average fiber length will be described later. Thus, hardwood pulp has a shorter fiber length than softwood pulp. In the napkin 1 of this embodiment, hardwood pulp is used for the absorbent body 10. As a result, the average fiber length of the water-retaining fibers is shortened (see FIG. 13).

Moreover, the density of the absorber 10 is 0.04 g/cm ³ or more and less than 0.3 g/cm ³ (described later). Thereby, body fluids can be diffused smoothly and absorbency can be ensured.

Thermoplastic resin fibers include, for example, single fibers made of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), etc., fibers made by polymerizing PP and PE, or fibers made by polymerizing PP and PE. Examples include composite fibers with a core-sheath structure. Furthermore, it is possible to adjust the degree of crimp in thermoplastic resin fibers. For example, the fibers can be crimped by using core-sheath type or eccentric type composite fibers made of two synthetic fiber components having different melting points as the thermoplastic resin fibers.

In this embodiment, the average fiber length of the thermoplastic resin fibers is about 30 mm. Further, the average number of crimps per unit length of the thermoplastic resin fiber is determined to be smaller than the average number of crimps per unit length of the water-retaining fiber. This reduces entanglement between the thermoplastic resin fibers and the water-retaining fibers, making it possible to achieve a soft finish. Therefore, even when thermoplastic resin fibers are included, the wearing comfort can be improved and the leakage prevention property can be improved.

To measure the average number of crimps, for example, sample multiple test pieces (for example, 5 cm square test pieces) in the width direction, and use a microscope VH-Z450 manufactured by Keyence Corporation to measure the number of crimps in the test piece. The number of crimps per inch (2.54 cm) may be measured several times with no load applied to the fibers. The number of crimps (average number of crimps per unit length) can be calculated from the average value.

Further, as fibers added to or in place of the thermoplastic resin fibers, water-retentive fibers such as rayon fibers may be used. That is, the absorbent body 10 includes at least one of rayon fibers and synthetic fibers (thermoplastic resin fibers). In this case, the rigidity of the absorbent core is improved, so that deformation of the absorbent core is suppressed, and a decrease in fit can be suppressed. Further, by using rayon fiber, the absorbency of the absorbent body 10 can be further improved.

Further, the absorbent body 10 may contain fibers other than those mentioned above, for example, may contain natural fibers such as cellulose.

Further, liquid-absorbing granules such as super-absorbent polymers (so-called SAP) may be added.

As a method for manufacturing the absorbent body 10, a method of accumulating pulverized pulp, superabsorbent polymer, etc. is known.

FIG. 4 is a diagram for explaining a method of manufacturing the absorbent body 10. Here, a case will be described in which an absorbent body 10 containing water-retentive fibers, thermoplastic resin fibers, and superabsorbent polymer (SAP) is manufactured.

The rotating drum 70 is a hollow cylindrical drum, and a plurality of recesses 71 are formed at a predetermined pitch on the circumferential surface as molds for filling absorbent material. When the rotary drum 70 rotates and the recess 71 enters the material supply section 80 , the absorbent material supplied from the material supply section 80 is deposited (accumulated) in the recess 71 due to the suction of the suction section 72 .

The material supply section 80 with a hood 80a is formed to cover the upper part of the rotating drum 70, and the material supply section 80 is configured to produce pulverized pulp (softwood pulp, hardwood pulp) obtained by pulverizing a pulp sheet with a pulverizer (not shown). (which corresponds to pulverized fibers) and a thermoplastic resin is supplied to the recess 71 by air conveyance. Further, the material supply section 80 includes a particle supply section 81 that supplies super absorbent polymer particles, and supplies the super absorbent polymer particles to the recess 71 . The mixture of water-absorbing fibers and thermoplastic resin fibers and the super-absorbent polymer particles are deposited in the recess 71 in a mixed state, and the absorber 10 is formed in the recess 71 .

Due to further rotation of the rotating drum 70, when the recess 71 containing the absorbent body 10 reaches the lowest part of the drum, the absorbent body 10 is removed from the recess 71, and the base material (cover sheet 6, etc.) conveyed by the conveyor is removed. It will be placed on top and passed on to the next process.

In addition, in the subsequent process, for example, when joining the second sheet 4 and the absorbent body 10 with a hot melt adhesive (HMA) or the like, the second sheet 4 is pressed against the absorbent body 10. That is, since the absorbent body 10 is pressed in the thickness direction in the subsequent steps, the fiber density is higher at both ends in the thickness direction than in the center.

Then, on the skin side of the absorbent body 10, for example, it is possible to suppress the hot melt adhesive applied to the skin side for joining the second sheet 4 from penetrating into the center of the absorbent body 10. 10 can be finished softly. In addition, on the non-skin side of the absorbent body 10, a capillary effect occurs from the center in the thickness direction to the non-skin side, improving the diffusivity of excreted liquid. The whole of 10 can be used to hold the excretory fluid.

Further, by pressing the second sheet 4 and the absorbent body 10 in the thickness direction, the water-retentive fibers of the absorbent body 10 are entangled with the fibers of the second sheet 4. FIG. 5 is an explanatory diagram showing how the fibers of the second sheet 4 and the fibers of the absorbent body 10 are intertwined. As will be described later, since hardwood pulp is thin, the fibers tend to get stuck in between the fibers, causing entanglements, whereas softwood pulp is thick, so it is difficult to get between the fibers, making it difficult for such entanglements to occur (or not). In other words, the water-retentive fibers in FIG. 5 represent hardwood pulp.

Looking at FIG. 5, inside the second sheet 4, the water-retentive fibers 10f (indicated by black lines in the enlarged view) of the absorber 10 are in contact with the fibers 4f (indicated by white lines in the enlarged view) of the second sheet 4. ing. That is, at least a part of the water-retentive fibers 10f (pulverized fibers) made of hardwood protrude from the skin-side surface of the absorbent body 10 and extend to the inside of the second sheet 4. At least a portion of the water-retentive fibers 10f (pulverized fibers) made of hardwood are in contact with the fibers of the second sheet 4.

Due to this contact between the fibers, the excretory liquid can easily enter the interior of the absorbent body 10 through the water-retaining fibers 10f from the fibers 4f of the second sheet 4, so that the liquid absorption speed can be increased. Moreover, since the water-retaining fibers become caught in the skin-side sheet, twisting of the absorbent body 10 can be suppressed, and deformation of the absorbent body 10 can be suppressed.

As a comparative example (described later) of the absorbent body 10, an absorbent body 10 was prepared by forming a sheet (airlaid) of pulp fibers, thermoplastic resin fibers, powder, etc. described in Patent Document 1 using the same manufacturing method (airlaid method) as for nonwoven fabrics. I am using it. A binding material is added to the airlaid, and by using such a binding material, the rigidity of the absorbent body 10 becomes higher than that manufactured by the manufacturing method shown in FIG. reduce In other words, when the absorbent body 10 is manufactured using the manufacturing method shown in FIG. 4, the absorbent body 10 is manufactured with lower rigidity (softer) and higher liquid dispersibility and liquid absorbency than an absorbent body manufactured by the air-laid method. be able to.

In other words, in the absorbent body manufactured by the air-laid method, the absorption and diffusion of excreted liquid is inhibited by the binder, and the liquid absorbency and liquid diffusivity are reduced, but the absorbent body 10 manufactured by the manufacturing method shown in FIG. Since it is formed by intertwining pulverized pulp fibers (hardwood pulp and softwood pulp), excreted liquid is smoothly absorbed and diffused (high liquid absorbency and liquid dispersibility).

Further, the thickness of the absorber 10 is desirably 2 mm or more and 10 mm or less. If the thickness of the absorbent body 10 is less than 2 mm, it will be too thin and will twist, and if it exceeds 10 mm, it will be too hard and the wearer may feel uncomfortable.

Further, since hardwood pulp is thinner than softwood pulp and has a shorter distance between fibers, when compared under the same density conditions, the fiber number density of hardwood pulp is higher than that of softwood pulp. Note that the fiber number density corresponds to the average number of fibers per unit area, and is a value calculated by calculating the number of fibers included per unit area in the case of a close-packed structure using fiber thickness + average inter-fiber distance. . Looking at this trial value, the fiber number density of hardwood pulp is 1182.2 fibers/mm ² , which is about six times the fiber number density of softwood pulp (200.3 fibers/mm ² ).
Therefore, when hardwood pulp is used, higher density can be achieved than when softwood pulp is used.

The fiber number density is preferably 300 fibers/mm ² or more and less than 2,500 fibers/mm ² . If the fiber number density is less than 300 fibers/mm ² , the absorbent body 10 will become thin and twist during use, resulting in a decrease in the area of the absorbent body and a tendency to leak. If the fiber number density is 2,500 fibers/mm ² or more, the absorbent body 10 will be too stiff and uncomfortable during use. When the fiber number density is 300 fibers/mm ² or more and less than 2,500 fibers/mm ² , the capillary effect can be enhanced, and the film can be made thinner and more flexible, thereby increasing absorbency.

Further, it is preferable that the fiber number density of hardwood pulp is higher than that of softwood pulp. In this way, the capillary effect can be increased while maintaining the softness of the absorbent body 10.

Further, in the absorbent body 10 containing thermoplastic resin fibers, it is desirable that the thermoplastic resin fibers are fused to each other in the pressing section 40 that integrally compresses the absorbent body 10 in the thickness direction. That is, the absorbent body 10 includes a plurality of thermoplastic fibers and has a compressing section 40 that integrally compresses the absorbent body 10 in the thickness direction, and in the compressing section 40, the thermoplastic fibers are fused to each other. It is desirable that you do so.

That is, when forming the compressed portion 40, the thermoplastic fibers are fused to each other, thereby strengthening the integrity of the top sheet 3 and the absorbent core 10, and making it easier to stabilize the shape of the absorbent core 10. Thereby, even if, for example, the wearer moves his or her body significantly while wearing the napkin 1, it is possible to easily prevent the absorbent body 10 from losing its shape or from deteriorating its water absorbency. .

Note that if the thermoplastic fibers are thermally bonded to each other in a portion of the absorbent body 10 other than the compressed portion 40, the absorbent body 10 may become hard or form a film at the location where the thermal bonding occurs. Problems such as a decrease in liquid diffusivity may occur. On the other hand, since the compressed portion 40 of the absorbent core 10 is a region where the absorbent core 10 is deformed by being compressed and made hard, the thermoplastic fibers in this region may be thermally fused to each other and become hard. The effect of a decrease in liquid diffusivity is small. Therefore, even if the thermoplastic fibers are fused to each other in the compressed portion 40 of the napkin 1, problems are unlikely to occur.

<<About the pressing section 40>>
Next, the compressing section 40 will be explained. As shown in FIG. 1, the napkin 1 according to the present embodiment has a plurality of types of pressing portions 40 (hereinafter, a typical pressing portion 40 will be used to make the explanation easier to understand). In the wing area WA of the napkin 1, a first compressed part 40a is compressed into a circular shape, and a second compressed part 40b (corresponding to the central hinge part) extending in the longitudinal direction and having a predetermined dimension (corresponding to the vertical dimension described later) equivalent) is provided.

A third pressing section 40c extending in the width direction is provided on the front and rear sides of the second pressing section 40b. Further, a fourth pressing section 40d (corresponding to a peripheral pressing section) is provided on the outer peripheral edge of the napkin 1, in which the side sheet 2, back sheet 5, etc. are compressed along the outer peripheral edge. A fifth compressed portion 40e (corresponding to a low-density compressed portion) compressed into a wave shape when viewed in the thickness direction is provided outside the second compressed portion 40b in the width direction.

FIG. 6 is a schematic cross-sectional view of the pressing section 40 taken along the line BB in FIG. As shown in FIG. 6, in the sixth compressed portion 40f, only the absorbent body 10 is compressed from both sides in the thickness direction toward the center.

In other words, the first pressing section 40a to the sixth pressing section 40f compress different members, and the first pressing section 40a to the third pressing section 40c and the fifth pressing section 40e use the top sheet 3, the second The sheet 4 and the absorbent body 10 are integrally compressed (corresponding to a hinge part), and the fourth compressed part 40d is formed by integrally compressing the side sheet 2 and the back sheet 5 (not including the absorbent body 10). Only the absorbent body 10 is compressed in the sixth compressed portion 40f.

That is, the compressed part has a hinge part in which the absorbent core 10 and the sheets (top sheet 3 and second sheet 4) on the skin side of the absorbent core 10 are compressed together. Hardwood water-retentive fibers are less entangled than softwood water-retentive fibers, and the absorbent body 10 containing hardwood water-retentive fibers tends to twist easily, so a hinge portion is provided (the absorbent body 10 is and is integrated with the second sheet 4), it is possible to suppress twisting of the absorber 10. In addition, since the top sheet 3 and the absorbent core 10 are pressed together, the distance between the top sheet 3 and the absorbent core 10 is reduced, which improves liquid transfer to the absorbent core 10 while suppressing twisting. be able to.

Note that the compressing member is not limited to the one shown in FIG. 6, and may compress everything from the backsheet 5 to the absorbent core 10 in one piece. Furthermore, the arrangement pattern of the pressing portions is not limited to that shown in FIG. 1.

Further, as shown in the enlarged view C of FIG. 1, a part of the hinge portion (here, the second compressed portion 40b is shown as an example) is compressed so that the density of the compressed portion 40 is in two stages. There is. That is, the hinge portion includes a base compressed portion Lp and a high-density compressed portion Hp compressed in the base compressed portion Lp to a higher density than the base compressed portion Lp.

Further, as shown in FIG. 6, the fifth pressing section 40e, which is a part of the pressing section 40 (hinge section), is, for example, the same as or more compressed than the base pressing section Lp of the second pressing section 40b. The groove density is low (the groove depth in the thickness direction is deep). That is, the hinge portion includes a low-density compressed portion that is the same as the base compressed portion Lp or in which the absorbent core 10 is compressed to a lower density than the base compressed portion Lp.

In addition, although it has already been mentioned that the fifth pressing section 40e (low-density pressing section) has a wave shape, the wave shape makes it difficult for force to concentrate at one point compared to a straight line shape, so the linear pressing section 40e has a wave shape. Compared to this, the napkin 1 can be prevented from losing its shape (particularly in situations where the wearer violently moves both legs back and forth (such as playing sports)). In addition, the hinge part shown by the wave shape in FIG. 1 is not restricted to the low-density compression part of the 5th compression part 40e, For example, the compression density may be about the base compression part Lp. That is, if the shape of the hinge portion is wavy when viewed from the thickness direction, the same effect can be obtained.

<About the horizontal and vertical dimensions of the pressing part>
Next, the horizontal dimension (corresponding to the first dimension) and vertical dimension (corresponding to the second dimension) of the pressing section 40 will be explained. FIG. 7 is an explanatory diagram for explaining the horizontal and vertical dimensions of the pressing section, with the upper diagram showing the second pressing section 40b, the center diagram showing the third pressing section 40c on the front side, and the lower diagram showing the first pressing section 40a. As an example, triangular pressing portions are shown. In FIG. 7, the horizontal dimension is represented by a solid line arrow, and the vertical dimension is represented by a broken line arrow.

Although it has already been mentioned that the second compressed portion 40b extends in the longitudinal direction, the more accurate direction in which it extends is the direction of the broken line shown in the upper diagram of FIG. In other words, the second pressing section 40b extends in a curved manner in the longitudinal direction, and the dimension of this curve (the dimension when the second pressing section 40b is made straight) is the vertical dimension of the second pressing section 40b. . The dimension perpendicular to the vertical dimension (the tangent to the vertical dimension) is the horizontal dimension of the second pressing section 40b. In other words, the second pressing section 40b has a plurality of horizontal dimensions, and the horizontal dimension shown in the upper diagram of FIG. 7 (solid line arrow) is the maximum value of the horizontal dimension of the second pressing section 40b (in FIG. The same shall apply hereinafter).

Looking at the direction in which the third pressing section 40c extends, for example, as shown in the center view of FIG. and a third compressing lower side 40cb extending in a curved shape in the width direction and protruding upward in the plane of the paper. That is, the third pressing section 40c can be said to be one pressing section configured by combining a plurality of pressing sections. In a compressing section composed of a plurality of compressing sections such as the third compressing section 40c, each disassembled compressing section has its own vertical dimension and horizontal dimension.

In other words, the third pressing section upper side 40ca has a vertical dimension extending in a curved direction diagonally upward to the left of the paper, a horizontal dimension perpendicular to the vertical dimension, and a vertical dimension extending curved diagonally upward to the right of the paper. , has a horizontal dimension perpendicular to the vertical dimension, and the third compression lower side 40cb has a vertical dimension extending in a curved shape in the width direction protruding upward from the plane of the paper, and a horizontal dimension perpendicular to the vertical dimension. ing.

In addition, although both the second pressing part 40b and the third pressing part 40c are the pressing parts 40 extending in a curved shape, they are not limited to this. For example, they may extend in a straight line, or they may extend in a straight line. A compressing section extending in a curved shape may be combined to form one compressing section.

Next, the compressed parts, such as the circular first compressed part 40a and the triangular compressed part shown in the lower diagram of FIG. The horizontal and vertical dimensions of a compressed portion (hereinafter also referred to as a dot-shaped compressed portion) whose vertical dimension is not sufficiently large and the direction in which it extends is unclear will be explained.

In the dot-shaped pressed part, when a straight line is drawn across the dot-shaped pressed part along a certain plane direction (direction represented by longitudinal and widthwise components), the outer edge of the dot-shaped rolled part and the straight line The dimension in which the distance between the intersection points is the maximum is defined as the straddling dimension of the dot-shaped compressed portion in a certain plane direction. That is, for example, in the lower diagram of FIG. 7, if a straight line is drawn along the vertical direction of the page as a certain plane direction, the first compressing part 40a draws a straight line passing through the center of the circle (a straight line indicated by a broken line arrow), a triangular In terms of the shape, the perpendicular line of the triangle (the straight line indicated by the solid arrow) is the straddle dimension of each dot-shaped compressed part in the vertical direction.

Then, when the straddling dimension of the dot-shaped compressed portions is viewed in all directions in the plane direction, the dimension where the straddling dimension is the shortest is the lateral dimension. That is, the lateral dimension of the dot-shaped compressed portion is the shortest straddle dimension among the straddle dimensions of the dot-shaped compressed portion. Then, in the first compressed portion 40a, straight lines (diameters) in all directions passing through the center of the circle have the same length, and all the straddle dimensions can be said to be the shortest straddle dimensions. In the first pressing section 40a shown in the lower diagram of FIG. 7, in order to make the explanation easier to understand, the horizontal dimension is taken in the left-right direction of the page. In addition, in a triangular compressed part, the perpendicular from the vertex with the largest internal angle is the shortest straddle dimension (lateral dimension). In the lower diagram of FIG. 7, it is the straddling dimension in the vertical direction of the page. The vertical dimension of the dot-shaped compressed portion is a dimension perpendicular to the horizontal dimension. That is, in the first pressing section 40a, the vertical dimension is the straddling dimension in the vertical direction of the page, and in the triangular pressing section, the vertical dimension is the straddling dimension in the horizontal direction of the page.

Moreover, when looking at the relationship between the horizontal dimension and the vertical dimension of the pressing section 40, it is found that in the circular first pressing section 40a, the horizontal dimension and the vertical dimension are the same length, and the other pressing sections 40, the vertical dimension is longer than the horizontal dimension. In other words, the pressing section 40 has a horizontal dimension (first dimension) and a vertical dimension (second dimension) that is perpendicular to the horizontal dimension (first dimension) and has a length equal to or longer than the horizontal dimension (first dimension). are doing.

<<About the average fiber length of water-retaining fibers>>
Next, the relationship between the average fiber length of the water-retentive fibers and the compressed portion 40 and the adhesive portion 21 for the main body portion will be explained. First, the relationship with the pressing part 40 will be explained, and then the relationship with the main body adhesive part 21 will be explained. As described above, the absorbent body 10 uses general softwood pulp and soft hardwood pulp with a short average fiber length as water-retentive fibers. As shown in FIG. 3, the average fiber length of the hardwood pulp is 0.79 mm, and the average fiber length of the softwood pulp is 2.5 mm.

The maximum value (approximately 1.0 to 2.0 mm) of the horizontal dimension (first dimension) of the pressing section 40 according to the present embodiment is larger than the average fiber length (0.8 mm) of the hardwood pulp, and is smaller than the average fiber length (2.5 mm).

In addition, the dimension of the compression part 40 based on this embodiment means the dimension between the compression start points where the compression part 40 begins to become depressed in the thickness direction in a plane direction. Taking the lateral dimension of the first pressing part 40a as an example, as shown in the enlarged view of FIG. 6, it is the lateral dimension La between the pressing start point La1 and the pressing start point La2 where the first pressing part 40a starts to become depressed.

FIG. 8 is a schematic cross-sectional view showing the pressing section of hardwood pulp 50L and softwood pulp 50N, where FIG. 8a is the pressing section of hardwood pulp 50L (100%), and FIG. 8b is the pressing section of softwood pulp 50N (100%). , FIG. 8c shows the compressed portion of the absorbent body 10 in which hardwood pulp 50L (50%) and softwood pulp 50N (50%) are mixed. In the figure, dimension L is the maximum horizontal dimension of the pressed part (approximately 1.0 to 2.0 mm), dimension LL is the average fiber length of 50L hardwood pulp, 0.8 mm, and dimension LN is the average fiber length 2 of softwood pulp 50N. Each represents .5mm. In addition, in FIG. 8, in order to make the explanation easier to understand using left and right, the horizontal dimension is the dimension in the width direction.

As shown in FIG. 8, the number of water-retentive fibers that straddle the left and right boundaries ED in the width direction of the pressing section differs depending on whether the hardwood pulp 50L or the softwood pulp 50N is used. In the case of the hardwood pulp 50L (FIG. 8a), the dimension L of the pressed part is larger than the fiber length dimension LL of the hardwood pulp 50L, so if the pressed part and the hardwood pulp 50L overlap in the thickness direction, at the boundary ED of the pressed part. Straddling of fibers may or may not occur. For example, in FIG. 8a, the water-retentive fibers straddle at two locations: the upper left boundary P1 and the lower left boundary P2. On the other hand, in the case of softwood pulp 50N (Fig. 8b), the dimension L of the pressed part is smaller than the fiber length dimension LN of the softwood pulp 50N, so if the pressed part and the softwood pulp 50N overlap in the thickness direction, the boundary of the pressed part Fiber straddling occurs in ED. For example, as shown in FIG. 8b, the water-retaining fibers straddle at both the left and right boundaries ED, and the water-retaining fibers straddle at about 10 locations. When the water-retentive fibers straddle the boundary ED of the compressed part, the boundary ED of the compressed part becomes harder than when the water-retentive fibers do not straddle the boundary ED of the compressed part.

When the absorbent body 10 according to the present embodiment includes hardwood pulp 50L having an average fiber length less than or equal to the maximum horizontal dimension of the compressed portion 40, compared to water-retentive fibers made only of general softwood pulp 50N. Alternatively, there is an effect that straddling of the water-retentive fibers is reduced compared to the case where the hardwood pulp 50L having an average fiber length larger than the maximum lateral dimension of the pressing section 40 is included. For example, in FIG. 8c, there are 6 locations where the water-retentive fibers straddle, which is fewer than the 10 locations for the softwood pulp 50N (100%) shown in FIG. 8b. In other words, in water-retentive fibers (FIGS. 8a and 8c) containing hardwood pulp 50N having an average fiber length less than or equal to the maximum horizontal dimension of the compressed part 40, the hard part of the boundary ED of the compressed part is reduced, and the wearer This reduces the number of parts that feel hard, making it more comfortable to wear.

Furthermore, when the water-retentive fibers straddle the boundary ED of the compressed part, the boundary ED of the compressed part becomes less likely to deform than when the water-retentive fibers do not straddle. FIG. 9 is an explanatory diagram for explaining the deformation of the compressed part of the hardwood pulp 50L, the left diagram is an explanatory diagram when the left boundary part of the compressed part is deformed inward, and the center diagram is the diagram of the compressed part deformed inward. This is an explanatory diagram when the right side boundary part is deformed inward, and the right diagram is an explanatory diagram when the pressing part is deformed starting from the end 50Le of the hardwood pulp 50L.

Comparing the left diagram and the center diagram of FIG. 9, when deforming the left diagram, it is necessary to deform the hardwood pulp 50L that straddles the upper left boundary P1 and the hardwood pulp 50L that straddles the lower left boundary P2. On the other hand, when the center view is deformed, there is no hardwood pulp 50L spanning the upper right boundary portion P3 and the lower right boundary portion P4, so the deformation is easier than in the left view.

Further, as the average fiber length of the water-retaining fibers becomes shorter, the number of straddles of the water-retaining fibers decreases, resulting in more deformation starting from the end portion 50Le of the water-retaining fibers as shown in the right diagram of FIG. That is, in the absorbent body 10, deformation starting from the end portion 50Le occurs more often in the hardwood pulp 50L than in the softwood pulp 50N.

For the wearer, the compressed part is more likely to deform as shown in the center figure, and the absorbent article in which the compressed part is more deformed as shown in the right figure is better than the absorbent article in which the upper left boundary part P1 is more likely to deform as shown in the left figure. It is more comfortable to wear than an absorbent article that is hard and does not easily deform.

In other words, in the case of the absorbent body 10 containing 50L of hardwood pulp, as mentioned above, there is an effect of reducing the straddling of the water-retentive fibers in the compressed part. Compared to an absorbent body, it is possible to reduce the number of water-retentive fibers that straddle the boundary ED (end of the squeezed part 40) between the squeezed part 40 and the non-pressed part (absorbent body 10), and when the squeezed part 40 is deformed, It is possible to provide a napkin 1 that has reduced perceived hardness and is comfortable to wear.

Moreover, when comparing the maximum value (approximately 2.0 mm) of the lateral dimension Lb (dimension of the base pressed part Lp part) of the second pressing part 40b and the average fiber length LL of the hardwood pulp 50L, it is found that the second pressing part 40b (center hinge The maximum value of the lateral dimension Lb (first dimension) of the hardwood pulp is larger than the average fiber length LL of the hardwood pulp.

Therefore, in the second compressed part 40b (center hinge part), it is possible to reduce the amount of water-retentive fibers that straddle the boundary ED between the compressed part 40 and the non-pressed part (absorbent body 10), so that when the compressed part 40 is deformed, It is possible to provide a napkin 1 that has reduced hardness felt by the body and is comfortable to wear. Furthermore, because the fiber width of hardwood is narrow, the fibers that straddle each other are easier to bend than those of softwood. It can be said that this provides an even more comfortable wearing experience.

In addition, as shown in the enlarged view of FIG. 6, in the above, the horizontal dimension La is set between the compression start point La1 and the compression start point La2 where the first compression part 40a starts to become depressed, but the lower left boundary of the compression part shown in FIG. 8a It is good also as a dimension between the compression start points at which the bottoms of the portion P2 and the lower right boundary portion P4 begin to curve. In this case, the lower left boundary part P2 and the lower right boundary part P4 become more easily bent, so that it is possible to provide a napkin 1 in which the hardness felt by the body when the compressed part is deformed is reduced and a comfortable wearing feeling is realized. can.

In addition, when comparing the maximum value (about 1.0 mm) of the dimension W in the longitudinal direction of the high-density pressed part Hp shown in the enlarged view C of FIG. 1 with the average fiber length LL of the hardwood pulp 50L, it is found that The maximum value of the dimension W in the direction is larger than the average fiber length LL of the hardwood pulp.

Therefore, in the high-density pressed part Hp, it is possible to reduce the water-retentive fibers that straddle the boundary ED between the high-density pressed part Hp and the low-pressed part (base pressed part Lp), making it easier to deform the hinge part in the longitudinal direction. be able to. In other words, the hinge portion can easily follow the roundness of the wearer's body, making it easier to fit the wearer's body. In addition, since it is easier to draw the liquid in the thickness direction than when the excreted liquid spreads in the plane direction, leakage can be reduced. It becomes easier to move backwards, and the ability to draw in excretory fluid becomes worse).

Furthermore, when comparing the maximum value of the lateral dimension Le of the fifth pressing section 40e (approximately 1.0 mm) and the average fiber length LL of the hardwood pulp 50L, the maximum lateral dimension Le of the fifth pressing section 40e (low-density pressing section) is The value is greater than the average fiber length LL of hardwood pulp.

Therefore, in the fifth compressed part 40e (low-density compressed part), it is possible to reduce the amount of water-retentive fibers that straddle the boundary ED between the compressed part 40 and the non-pressed part (absorbent core 10), so that when the compressed part 40 is deformed, It is possible to provide a napkin 1 that has reduced hardness felt on the body and is comfortable to wear.

Moreover, when comparing the maximum value (about 1.0 mm) of the lateral dimension La of the first pressing section 40a (circular pressing section) and the average fiber length LL of the hardwood pulp 50L, it is found that the first pressing section 40a (circular pressing section) The maximum value of the lateral dimension La is larger than the average fiber length LL of the hardwood pulp.

Therefore, in the first compressed section 40a (circular compressed section), it is possible to reduce the amount of water-retentive fibers that straddle the boundary ED between the compressed section 40 and the non-squeezed section (absorbent body 10), so that when the compressed section 40 is deformed, It is possible to provide a napkin 1 that has reduced hardness felt on the body and is comfortable to wear.

In addition, in the thickness direction, the average fiber length of the water-retentive fibers is shorter than the thickness of the absorbent body 10, and the thickness of the high-density pressed portion Hp (from the bottom surface of the high-density pressed portion Hp to the non-skin side of the absorbent body 10) (distance to the surface). Then, on the non-skin side of the high-density pressed part Hp, the hardwood pulp is located along the plane direction, so it can have flexibility in the thickness direction (the hardwood pulp stands up (along the thickness direction)). ), the hardwood pulp functions to support the high-density pressed part Hp when the high-density pressed part Hp is pressed (for example, when worn), impairing its flexibility). That is, according to the absorbent body 10, it is possible to provide a napkin 1 with further reduced discomfort.

Next, the relationship between the average fiber length of the water-retentive fibers and the adhesive portion 21 for the main body portion will be explained. FIG. 10 is a schematic plan view of the napkin 1 viewed from the non-skin side in the thickness direction. As shown in FIG. 10, on the non-skin side of the backsheet 5, a main body adhesive part 21 extending in the longitudinal direction (corresponding to the first direction) is provided in the width direction (corresponding to the first direction) orthogonal to the longitudinal direction (first direction). A plurality of fibers are provided at intervals of 21g in the width direction (corresponding to two directions), and the minimum value of the widthwise (second direction) intervals of 21g is greater than the average fiber length of water-retentive fibers made of hardwood.

Therefore, when receiving a deforming force from the underwear, water-retentive fibers that straddle the outer edge of the adhesive part 21 for the main body part can be reduced, and the absorbent body 10 can easily bend between the adhesive parts 21 for the main part. , the napkin 1 is easily linked to the movement of the body, and the fit is improved.

In addition, although the main body adhesive parts 21 shown in FIG. 10 extend in the longitudinal direction and are provided in plurality at intervals of 21 g in the width direction, the present invention is not limited to this. They may be provided at intervals in the longitudinal direction.

===About the evaluation of the absorber 10==
Samples of the absorbent body 10 having different fiber components and manufacturing methods were prepared, and the following items such as the density of the compressed portion 40 and tensile strength were evaluated.

<<Evaluation of density and tensile strength of compressed part 40>>
The density and tensile strength of the compressed portion 40 were evaluated by changing the compressing conditions. Note that the pressing conditions were such that three types of embossing rolls with different pressing depths were used to form the pressing section, and each was set to pressing conditions 1 to 3.

Five samples of hardwood pulp and softwood pulp were prepared for each compression condition. Measure the weight of each sample on a direct scale (for example, electronic balance HF- manufactured by Kensei Kogyo Co., Ltd.).
300), 0.2 g was prepared, spread to a length of 38 mm x width of 25 mm, and then a top sheet 3 and a second sheet 4 of the same shape were stacked on top of each other, and each was pressed integrally under the above conditions to obtain a measurement sample. Then, the thickness of the measurement sample was evaluated (measured) by the following method, and the density was calculated by dividing the weight (0.2 g) by the volume (thickness x sample area).

<Thickness evaluation method>
To evaluate the thickness, freeze the measurement sample in liquid nitrogen, cut it across the target area, and examine the cut surface using a digital microscope VHX-100 (lens VH-Z20R + variable illumination attachment VH) manufactured by Keyence Corporation. -K20), a cross-sectional image of the target part of the measurement sample was photographed and measured with a measurement area of 20 mm in length x 20 mm in width.

<Tensile strength evaluation method>
FIG. 11 is an explanatory diagram for explaining the tensile strength evaluation method, and the left figure shows a schematic cross-sectional view of a normal compressed part 40, and the right figure shows a schematic cross-sectional view of the compressed part 40 during a tensile test. . The tensile strength test is carried out by removing the top sheet 3 and second sheet 4 on the left side of the left border of the compressed part 40 from the absorbent body 10 and folding them toward the right side, as shown in the figure on the right. (If included, fold the skin-side and non-skin-side core wrap sheets to the right in the same way, and also fold the back sheet 5 to the right).

That is, as shown by the white arrow in the right figure, the top sheet 3 and second sheet 4 folded to the right are pulled to the right, and the absorbent core 10 from which the top sheet 3 and second sheet 4 have been removed is pulled to the left. Then, as shown by X in the right figure, the maximum value of the tensile force when the top sheet 3, second sheet 4, and absorber 10 break is measured as the tensile strength. In addition, in FIG. 11, the direction penetrating the plane of the paper is the width direction, and the tensile strength of the compressed part 40 for a width of 25 mm is evaluated (the width of the compressed part 40 is based on 25 mm, so the denominator of the unit is 25mm).

FIG. 12 shows the evaluation results of the density (Table 1) and tensile strength (Table 2) of the compressed portion 40. Generally, the density of the compressed portion 40 is preferably 0.2 g/cm ³ or more and less than 0.8 g/cm ³ , and the joint portion between the absorber 10 and the compressed portion 40 (in this embodiment, the welded portion with the second sheet 4) It is desirable that the tensile strength, which is the maximum tensile force at the time of breaking due to tension, is 0.5 N/25 mm or more and less than 1.0 N/25 mm. In other words, if the density of the compressed part 40 is less than 0.2 g/cm ³ , the strength will be insufficient and it will be easily damaged (easily twisted), and if it is more than 0.8 g/cm ³ , it will be hard and feel uncomfortable when worn. . Moreover, if the tensile strength is less than 0.5 N/25 mm, the strength will be insufficient and it will be easy to break, and if it is more than 1.0 N/25 mm, it will be hard and easy to feel uncomfortable when worn.

Looking at FIG. 12, the density of the compressed part 40 is 0.2 g/cm ³ or more and less than 0.8 g/cm ³ and the tensile strength is 0.5 N/25 mm or more and less than 1.0 N/25 mm. These are compression conditions 2 and 3 for hardwood pulp. In other words, the above conditions do not apply to the absorbent body 10 made of softwood pulp, which is commonly used, as it has a lot of fiber entanglement and high tensile strength, and by using hardwood pulp (used in combination with softwood pulp), twisting can be suppressed. It is possible to provide a comfortable napkin 1 with less discomfort when worn.

<<Evaluation of absorber density and average fiber length>>
The absorbent density and average fiber length were evaluated. See Figure 13 for sample conditions.

As an example, an absorbent body containing hardwood pulp and manufactured by the manufacturing method shown in FIG. 4 was used as a sample. Here, hardwood pulp and thermoplastic resin fibers with an average fiber length of 6 to 70 mm were mixed at a predetermined ratio (Examples 1 and 2), and hardwood pulp and softwood pulp were mixed at a predetermined ratio (Example 3). , 4), and one using only hardwood pulp (Example 5) were evaluated.

Comparative examples included samples in which the absorbent body did not contain hardwood pulp (Comparative Examples 1, 2, and 4), and samples in which the absorbent body was manufactured by an air-laid method (Comparative Examples 3 and 4). Although Comparative Example 3 contains hardwood pulp, it is manufactured by the air-laid method, so a binder is added to the absorbent body.

<Absorber density evaluation method>
A plurality of absorber samples having a size of 10 mm in length x 40 mm in width were prepared as absorber samples under each condition of Examples and Comparative Examples, and the thickness of the absorber samples was measured using the thickness evaluation method described above. In addition, the basis weight (g/cm ² ) of the absorbent sample was calculated by measuring the weight using a direct balance (for example, electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.). Then, the absorber sample density (g/cm ³ ) was calculated from the absorber sample basis weight and the absorber sample thickness. It should be noted that approximately 5 samples were measured, and the average value was taken as the sample density. In addition, if a size of 10 mm length x 40 mm width cannot be obtained, sample at the maximum width and maximum area, and measure at least twice the number of samples N.

<Fiber length evaluation method>
Fiber length was measured in the same area as the absorber density evaluation.

Note that the average fiber length means a length-weighted average fiber length as measured by the center fiber length (Cont). The length-weighted average fiber length was calculated using Kajaani FiberLab fiber properties (off-line) manufactured by Metso Automation.
] is measured as the L(l) value. Note that this is also a method recommended by JIS P 8226-2 (Pulp-engineering automatic analysis method based on fiber length measurement method, based on non-polarized light method). Further, as described in the JIS evaluation method, the average fiber length and the fiber width described below are the results of measurements excluding fiber lumps.

In addition, the average fiber length of fibers other than pulp fibers is determined by measuring the average fiber length of JIS L 1015:2010, Annex A, "A7.1 Measurement of fiber length," "A7.1.1 A method (standard method). Measure according to the method for measuring the length of individual fibers on a board. The above method is a test method corresponding to ISO 6989 published in 1981.

FIG. 13 is a diagram (Table 3) showing the evaluation results of absorber density and average fiber length of water-retaining fibers. If the average fiber length of the water-retaining fibers contained in the absorbent body is long, the rigidity of the absorbent body increases at the compressed portion of the absorbent body, resulting in a hard finished product as described above. For example, if softwood pulp fibers are used as water-retentive fibers in the absorbent material of sanitary napkins, which are generally called thin, the compressed part of the absorbent material becomes too hard, which may cause discomfort to the wearer. .

On the other hand, in Examples 1 to 5, the average fiber length of the water-retaining fibers was shortened due to the inclusion of hardwood pulp. In other words, the napkins having the absorbent bodies of Examples 1 to 5 are napkins that feel less hard to the body and are more comfortable to wear.

In Comparative Example 1, Comparative Example 2, and Comparative Example 4, since hardwood pulp is not used, the average fiber length is 2.5 mm, which is longer than Examples 1 to 5. As already mentioned, the wearer tends to feel uncomfortable (hardness) when the compressed portion 40 is deformed. However, it is possible to reduce the hardness by, for example, reducing the absorbent basis weight. It is. However, in this case, there is a risk that the absorbent product will not function as an absorbent article due to a decrease in absorbency.

Further, in Comparative Example 3, the ratio of hardwood pulp to softwood pulp is the same as in Example 3, and the average fiber length is also less than 2 mm, but it is air laid and a binder is added. If a binder is added, the rigidity of the absorbent body 10 may increase even if soft hardwood pulp is used. In addition, since the binder reduces the liquid diffusivity and liquid absorption of the absorbent body 10, the effect of the hardwood pulp that improves the liquid diffusivity and liquid absorption becomes difficult to manifest.

Further, in Examples 1 to 5, the absorber density is 0.04 to 0.3 (g/cm ³ ). In napkins, if the absorbent density is less than 0.04 g/cm ³ , it is too soft and tends to lose its shape, and if it is 0.3 g/cm ³ or more, it is too hard and feels uncomfortable to the touch. In other words, when the absorbent density is 0.04 to 0.3 g/cm ³ , it is possible to provide a napkin with high liquid dispersibility that does not lose its shape and is comfortable to wear.

<<Average interfiber distance evaluation>>
The average interfiber distance of water-retaining fibers was evaluated by the following method.

The part corresponding to the sample to be measured was cut out into a rectangular shape (cut in the thickness direction) as the sample, and the 3D image linking function of a microscope (manufactured by KEYENCE VHX-2000, lens VH-Z20W aperture open) was used. Then, obtain an enlarged image that is in focus from the surface of the sample to a depth of 100 μm (for example, a 500x image for hardwood and a 100x image for softwood), and based on that enlarged image, identify the fibers that are in focus. Extracted the outside. The surface formed there is defined as a fiber space. The diameter of the maximum inscribed circle of the fiber space was defined as the fiber space distance, and the average value of 100 fiber spaces was defined as the average interfiber distance (Dp).

FIG. 14 is a diagram showing the average interfiber distance Dp of fibers. In the figure, the percentage of fibers (%) is the weight percentage of the fibers constituting the absorbent body 10. If the absorbent body 10 has a core wrap sheet, it is the weight percentage of the portion excluding the core wrap sheet, and if there is no core wrap sheet, it is the weight percentage of the fibers that constitute the absorbent body 10. It is a weight percentage. In this embodiment, there is no core wrap sheet.

As shown in FIG. 14, hardwood pulp has a smaller average interfiber distance than softwood pulp (18.7 μm for 100% hardwood and 50.0 μm for 100% softwood). Furthermore, by mixing them together, the average interfiber distance between hardwood pulp and softwood pulp becomes 27.7 μm for 50% hardwood and 50% softwood pulp.

In addition, when thermoplastic resin fibers with an average fiber length of 6 to 70 mm are mixed with softwood pulp, the average inter-fiber distance becomes smaller due to the mixture of thermoplastic resin fibers (mixing of softwood and thermoplastic resin fibers). The measured values are 32.3 μm and 36.7 μm, which are smaller than the 50.0 μm of 100% coniferous wood). Furthermore, when a similar thermoplastic fiber resin is mixed with hardwood pulp, the average inter-fiber distance increases due to the mixture of thermoplastic resin fibers (the mixture of hardwood and thermoplastic resin fibers has a 19. 0 μm, 32.3 μm, and 36.7 μm, which are larger than the 18.7 μm of 100% hardwood).

The average interfiber distance Dp is desirably 5 μm or more and less than 40 μm. Furthermore, it is desirable that the average inter-fiber distance Dp of the top sheet 3 and the second sheet 4 is larger than the average inter-fiber distance of the pulverized fibers (50 μm or more in this embodiment). By increasing the average distance between the fibers of the top sheet 3 and the second sheet 4, the excreted liquid will directly reach the absorbent body 10, and if the average distance between the fibers of the crushed fibers is less than 5 μm, the liquid will pass through. If the average distance between fibers is 40 μm or more, capillarity is difficult to occur and absorbency is reduced. In other words, by setting the average inter-fiber distance within this range, excretory fluid quickly reaches the absorbent core, the capillary effect is more likely to act, and an absorbent article with good absorbency can be provided.

<<Bending rigidity evaluation method>>
The bending rigidity of the napkin 1 was evaluated by measuring the torque value using the following method.

<Torque value measurement method>
The torque value in the longitudinal direction of the napkin 1 was measured. The measurement method was to attach chucks 25 mm x 25 mm above and below to an electric torque testing machine (DSP-10) manufactured by Nidec-Shimpo Corporation, with a distance between the chucks of 50 mm, a clockwise angular velocity of 30 rpm, and a rotation angle of 50 degrees. The angular speed of left rotation was 30 rpm, the rotation angle was 50 degrees, the number of repetitions was 1, the stopping time when switching from right to left rotation was 3 seconds, and the measurement angle was up to 45 degrees.

Multiple samples (for example, the shapes and sizes of the compressed parts are different) are prepared, and the measurement area is a range of the absorbent body that is longitudinally rearward than the vaginal opening contact area of the sample, and the sample is measured longitudinally in front. Removed unnecessary areas. Then, the sample was mounted on a chuck so that the center in the width direction was the center of rotation, and measurement was performed using the above measurement method.

The measurement result (torque value) was the maximum torque value during clockwise rotation, and was the average value of the number of samples N=5. The torque value of the napkin 1 is preferably 4 mN·m or more and less than 10 N·m. If the torque value of the napkin 1 is less than 4 mN·m, the napkin 1 will have insufficient bending rigidity and will tend to twist, while if it is 10 mN·m or more, the bending rigidity will be high and the napkin will feel uncomfortable when worn. In other words, it is possible to provide a napkin 1 that is suppressed from twisting and can be comfortably worn with less discomfort.

<<About the average fiber width of water-retaining fibers>>
Next, the average fiber width of the water-retaining fibers will be explained. Note that the measurement is performed in the same manner as for the average fiber length described above, and is measured as FiberWidth.

FIG. 15 is a diagram showing the average fiber width distribution of hardwood pulp and softwood pulp. The horizontal axis shows the fiber width (μm), and the vertical axis shows the frequency (%). As shown in FIG. 15, the average fiber width of the softwood pulp is about 30 μmm (upper figure), and the fiber width distribution is wide (standard deviation is 11.9). On the other hand, the average fiber width of hardwood pulp is about 15 μm (see the figure below), and the fiber width distribution width is narrow (standard deviation is 7.55). In the napkin 1 of this embodiment, by using hardwood pulp for the absorber 10, the average fiber width of the water-retentive fibers is shorter than when only softwood pulp is used.

The hardwood pulp has an average fiber width of 15 μm or less, a fiber number density of 300 fibers/mm ² or more and less than 2,500 fibers/mm ² as described above, and has a highly absorbent polymer between the hardwood pulps. is desirable. In this case, since the fibers are short and thin, the absolute fiber area is small, so the fibers are difficult to intertwine, and the hardwood pulp, which has a characteristic of short fiber width, is densely packed, so it is easy for excrement fluid to be included in the fibers. Therefore, the excreted liquid contained in the hardwood pulp is easily drawn into the superabsorbent polymer between the hardwood pulps, so that liquid return can be reduced even when the excreted liquid is absorbed multiple times.

Furthermore, looking at the distribution width, hardwood pulp has a narrower distribution width of fiber length (Fig. 3) and fiber width than softwood pulp. That is, the standard deviation of the fiber length of hardwood pulp is 0.27 or less, and the standard deviation of the fiber width of hardwood pulp is 7.55 or less. Furthermore, the value obtained by adding the standard deviation of the fiber length of hardwood pulp to the average fiber length of hardwood pulp (0.79 + 0.27 = 1.06) is twice the average fiber length of hardwood pulp (1.58). The value obtained by subtracting the standard deviation of the fiber length of hardwood pulp from the average fiber length of hardwood pulp (0.79 - 0.27 = 0.52) is 1/2 of the average fiber length of hardwood pulp. (0.395).

When the distribution width is narrow and the standard deviation is small in this way, it is easy to maintain a uniform fiber density in the absorbent body, so that it is easy to diffuse concentrically with less deviation in the plane direction.

In this way, when looking at the average fiber length and average fiber width of water-retentive fibers, compared to hardwood pulp, softwood pulp is thicker and longer, so the pulps tend to intertwine with each other and form a solid skeleton. . On the other hand, hardwood pulp is thin and short, so it is difficult for the pulps to intertwine with each other, but it is easy to get stuck between the softwood pulps, so by filling the skeleton made of softwood pulp with hardwood pulp, it becomes more resistant to twisting. It is possible to provide a napkin 1 with high liquid diffusion and rewetting properties.

===Other embodiments===
The above-described embodiments are provided to facilitate understanding of the present invention, and are not intended to be interpreted as limiting the present invention. It goes without saying that the present invention may be modified and improved without departing from its spirit, and that equivalents thereof are included in the present invention.

Further, in the above embodiment, the fourth compressing section 40d does not integrally compress the absorbent core 10, but the present invention is not limited to this. For example, a peripheral edge compressing section that compresses the outer periphery like a panty liner may integrally compress the absorbent body 10. In such a case, the maximum value of the lateral dimension of the peripheral compressed portion is larger than the average fiber length of the hardwood pulp (water-retaining fiber made of hardwood). That is, the pressing section 40 includes a peripheral pressing section compressed along the outer periphery of the napkin 1, and the maximum value of the horizontal dimension (first dimension) of the peripheral pressing section is longer than the average fiber length of the hardwood pulp. big.

In this way, in a peripheral compressed part such as a panty liner (when the top sheet 3, back sheet 5, etc. are compressed integrally with the absorbent body 10), water-retentive fibers that straddle the interface between the compressed part and the non-compressed part are reduced. Since the hardness of the peripheral edge portion is reduced, it becomes easier to return to the original shape when the peripheral edge portion is deformed, and deformation (folding tendency) of the peripheral edge portion can be suppressed.

Further, in the above embodiment, when forming the unevenness on the surface of the absorbent body 10, the unevenness is formed by squeezing, but the present invention is not limited to this. For example, the sixth pressing section 40f shown in FIG. 6 may have a low basis weight. That is, the absorbent body 10 is provided with a low basis weight portion where the basis weight of the absorbent body 10 is lower than the basis weight of the surrounding area, and the low basis weight portion forms a depression shape on the surface of the absorbent body 10. The maximum value of the lateral dimension (first dimension) of the low basis weight portion is larger than the average fiber length of the hardwood pulp.

By doing so, it is possible to reduce the amount of water-retaining fibers that straddle the ends of the low basis weight portion (low basis weight portion, etc.), and it is possible to make the low basis weight portion easily deformable in the width direction.

Furthermore, when a low basis weight section is used, such as the sixth compressed section 40f shown in FIG. The non-skin side surface of the low basis weight portion is located closer to the skin than the surface of the absorbent body 10 that is closest to the skin.

In this case, depressions are formed on both sides of the low basis weight portion in the thickness direction, so that the low basis weight portion can be easily deformed to both the skin side and the non-skin side.

Moreover, although the shape like the 6th compressed part 40f was illustrated above as a low basis weight part, it is not limited to this, and the shape where one of the skin side or the non-skin side is recessed may be sufficient. If the low basis rain volume part is provided on the skin side, the liquid drawing performance will be improved, and if it is provided on the non-skin side, it can be made easier to deform along the skin side.

Further, in the above embodiment, the napkin 1 does not have a core wrap sheet, but the napkin 1 is not limited to this, and may have a core wrap sheet. FIG. 16 is a schematic sectional view of the napkin 100 having the core wrap sheet 11, and corresponds to FIG. 2 of the above embodiment.

The core wrap sheet 11 is provided so as to cover the outer circumferential surface of the absorbent core 10, as shown in FIG. The core wrap sheet 11 can be exemplified by a liquid permeable sheet such as tissue paper or a nonwoven fabric, and is bonded to the absorber 10 with a core wrap bonding agent (HMA shown in enlarged view D) extending in the longitudinal direction. That is, the napkin 100 has a core wrap sheet 11 that covers the outer circumferential surface of the absorbent body 10, and the core wrap sheet 11 is formed by a core wrap bonding agent extending in the longitudinal direction and provided at intervals of 11 g in the width direction. It is joined to the absorber 10.

The minimum value of the interval 11g in the width direction of the core wrap bonding agent is larger than the average fiber length of the water-retentive fibers made of hardwood. Therefore, it is possible to reduce the amount of water-retentive fibers that straddle the outer edge of the core-wrap binder, and while the part to which the core-wrap binder is applied hardens the entire absorbent core, the part to which the core-wrap binder is not applied becomes easily deformed. Therefore, it is possible to provide a napkin 100 that is compatible with preventing the absorbent body 10 from losing its shape and having conformability.

In addition, although the core wrap bonding agent shown in FIG. 16 extends in the longitudinal direction and is provided in a plurality at intervals of 11 g in the width direction, the present invention is not limited to this. They may be provided at intervals.

Further, by providing the core wrap sheet 11, collapse of the absorbent core 10 can be suppressed. Although FIG. 16 shows an example in which one core wrap sheet 11 is used to wrap the absorbent core 10, it is also possible to provide only one of the skin side and non-skin side. Alternatively, the skin-side and non-skin-side sheets may be joined outside the outer edge of the absorbent core 10.

1 Sanitary napkins (absorbent articles)
2 Side sheet 3 Top sheet 4 Second sheet 4f Second sheet fiber 5 Back sheet 6 Cover sheet 10 Absorbent body (absorbent core)
10f Water-retentive fiber 11 Core wrap sheet 20 Napkin main body part 21 Adhesive part for main part 30 Wing part 31 Adhesive part for wing part 40 Compressed part 40a First compressed part (hinge part)
40b Second compression part (center hinge part)
40c Third compression part (hinge part)
40ca Third pressing section upper side 40cb Third pressing section lower side 40d Fourth pressing section (peripheral pressing section)
40e Fifth pressing section (low density pressing section. Hinge section)
40f 6th pressing section 50L Hardwood pulp (water-retentive fiber made of hardwood)
50N Softwood pulp 50Le End portion 70 Rotating drum 71 Recessed portion 72 Suction portion,
80 material supply section 80a hood,
81 Particle supply unit 100 Napkin (absorbent article)
ED Boundary Lp Base compressed part Hp High-density compressed part P1 Upper left boundary P2 Lower left boundary P3 Upper right boundary P4 Lower right boundary WA Wing area t1 Front extension start point t2 Rear extension start point

Claims (19)

It has a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other,
An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent core provided between the top sheet and the back sheet,
The absorbent core has crushed fibers,
The pulverized fibers include water-retentive fibers made of hardwood,
The absorbent core is provided with a compressed part in which the density of the absorbent core is higher than the density of the surrounding area,
The compressed portion has a first dimension and a second dimension that is orthogonal to the first dimension and has a length equal to or longer than the first dimension,
An absorbent article characterized in that a maximum value of the first dimension of the compressed portion is larger than an average fiber length of the water-retentive fibers made of the hardwood. The absorbent article according to claim 1,
The absorbent article is characterized in that the compressed portion has a hinge portion in which the absorbent core and a sheet on the skin side of the absorbent core are integrally compressed. The absorbent article according to claim 2,
The absorbent article is characterized in that the hinge portion is formed by pressing the top sheet and the absorbent core together. The absorbent article according to claim 2 or 3,
The absorbent article has a wing portion for fixing the absorbent article to the crotch of the wearer's underwear,
The hinge portion is arranged in a region between a front side extension start point and a rear side extension start point in the longitudinal direction where the wing portion extends outward in the width direction. It has a central hinge section with dimensions,
An absorbent article characterized in that a maximum value of the first dimension of the central hinge portion is greater than an average fiber length of the water-retentive fibers made of hardwood. The absorbent article according to any one of claims 2 to 4,
The hinge portion includes a base compression portion and a high density compression portion compressed in the base compression portion to a higher density than the base compression portion,
An absorbent article characterized in that a maximum dimension of the high-density compressed portion in the longitudinal direction is larger than an average fiber length of the water-retentive fibers made of hardwood. The absorbent article according to any one of claims 2 to 7,
An absorbent article characterized in that the hinge portion has a wavy shape when viewed from the thickness direction. The absorbent article according to any one of claims 1 to 6,
The compressed portion includes a peripheral compressed portion compressed along the outer periphery of the absorbent article, and the maximum value of the first dimension of the peripheral compressed portion is equal to the average of the water-retentive fibers made of the hardwood. An absorbent article characterized in that the fiber length is greater than the fiber length. The absorbent article according to any one of claims 1 to 7,
The absorbent article includes a second sheet made of fibers,
The second sheet is provided adjacent to the skin side of the absorbent core,
At least a portion of the pulverized fibers protrude from the skin-side surface of the absorbent core and extend into the interior of the second sheet,
An absorbent article characterized in that at least a portion of the crushed fibers are in contact with the fibers of the second sheet inside the second sheet. The absorbent article according to any one of claims 1 to 8,
An absorbent article characterized in that the absorbent core has a density of 0.04 g/cm ³ or more and less than 0.3 g/cm ³ . The absorbent article according to any one of claims 1 to 9,
The density of the compressed part is 0.2 g/cm ³ or more and less than 0.8 g/cm ³ ,
An absorbent article characterized in that a tensile strength, which is a maximum tensile force when the joint portion between the absorbent core and the compressed portion breaks due to tension, is 0.5 N/25 mm or more and less than 1.0 N/25 mm. The absorbent article according to any one of claims 1 to 10,
An absorbent article characterized in that the absorbent article has a torque value of 4 mN·m or more and less than 10 N·m. The absorbent article according to any one of claims 1 to 11,
The absorbent article includes a second sheet made of fibers,
In the absorbent core, a plurality of the pulverized fibers are intertwined with each other,
The average inter-fiber distance of the top sheet and the second sheet is larger than the average inter-fiber distance of the crushed fibers,
An absorbent article characterized in that the average interfiber distance of the pulverized fibers is 5 μm or more and less than 40 μm. The absorbent article according to any one of claims 1 to 12,
The absorbent core is provided with a low basis weight portion where the basis weight of the absorbent core is lower than the basis weight of the surrounding area,
The low basis weight portion forms a depression shape on the surface of the absorbent core,
An absorbent article characterized in that a maximum value of the first dimension of the low basis weight portion is larger than an average fiber length of the water-retentive fibers made of the hardwood. The absorbent article according to any one of claims 1 to 13,
A plurality of slip preventers extending in a first direction are provided on the non-skin side of the backsheet at intervals in a second direction perpendicular to the first direction,
An absorbent article characterized in that a minimum value of the spacing in the second direction of the anti-slip is larger than an average fiber length of the water-retaining fibers made of hardwood. The absorbent article according to any one of claims 1 to 14,
The absorbent article has a core wrap sheet that covers the outer peripheral surface of the absorbent core,
The core wrap sheet is bonded to the absorbent core by a core wrap bonding agent extending in the longitudinal direction provided at intervals in the width direction,
An absorbent article characterized in that the minimum value of the interval in the width direction of the core wrap binder is greater than the average fiber length of the water-retentive fibers made of hardwood. The absorbent article according to claims 1 to 15,
The average fiber width of the water-retentive fibers made of hardwood is 15 μm or less,
The number of water-retentive fibers made of hardwood contained per unit area of the absorbent core is 300 or more/mm2 or more and less than 2500/mm2,
An absorbent article characterized by having a superabsorbent polymer between a plurality of water-retaining fibers made of the hardwood. The absorbent article according to claims 1 to 16,
The standard deviation of the fiber length of the water-retentive fiber made of hardwood is 0.27 or less,
An absorbent article characterized in that the standard deviation of the fiber width of the water-retentive fibers made of hardwood is 7.55 or less. The absorbent article according to claim 17,
The value obtained by adding the standard deviation of the fiber length of the water-retaining fibers made of hardwood to the average fiber length of the water-retaining fibers made of hardwood is greater than twice the average fiber length of the water-retaining fibers made of hardwood. small,
The value obtained by subtracting the standard deviation of the fiber length of the water-retaining fibers made of hardwood from the average fiber length of the water-retaining fibers made of hardwood is 1/2 of the average fiber length of the water-retaining fibers made of hardwood. An absorbent article characterized in that it is larger than a value. The absorbent article according to claims 1 to 18,
The absorbent core includes a plurality of thermoplastic fibers and has a compressing part that integrally compresses the absorbent core in the thickness direction,
An absorbent article characterized in that the thermoplastic fibers are fused to each other in the compressed portion.

Images